Engine failure warning device



Oct. 28, 1947. w, BQURNE JR 2,429,920

ENGINE FAILURE WARNING DEVICE Filed July 11. 1945 f 7 INSULflT/OA/INVENTOR 8 [Wm/v0 fl. iawr/v-fi BY Wm b. ATT RN EY Patented Oct. 28,1947 UNITED STATES PATENT OFFICE ENGINE FAILURE WARNING DEVICE Edmund W.Bourne, Jr., Newark, N. Y. Application July 11, 1945, Serial No. 604.400

The invention here disclosed relates to the protection of aircraftengines.

In aircraft operations it is known that most engine failures areattributable to thepresence of metal particles, chips or cuttings in thelubrieating oil.

Special means are usually provided for screening out andfor enablingremoval of these metal pieces, but the effectiveness of such devicesdepends upon the attention given them, routine "inspection and the like,matters which can be and frequently are neglected.

Many engine failures could be prevented and lives and property be savedif it could be known in advance that a situation was developing whichmight cause engine failure. With notice in time, a pilot can takeprecautionary steps such as heading for the nearest landing field or, inthe case of a multi-engine ship, cutting out the engine where thedangerous condition is imminent, and the like.

The objects of this invention are to provide simple and practical meansreadily applicable to existing systems which will give the pilot awarning the instant metal cuttings or chips are present in thelubricating oil, in time, so far as possible,

'to enable him to take steps necessary to save the engine and all elsedepending on the operation of the engine.

These chips or cuttings may be of aluminum, bronze, brass, steel orother metals. It is therefore a particular object of the invention toprovide for the detection of any metal chips in the system,

both non-magnetic and magnetic.

Other objects of the invention are to provide warning means such asindicated which will not add objectionable bulk or weight and which whenin place will require no servicing or special attention.

Other desirable objects and the novel features by which the purposes ofthe invention are attained are set forth or will appear in the course ofthe following specification.

The drawing accompanying and forming part of the specificationillustrates a present practical embodiment of the invention. Structure,however, may be modified and changed as regards the immediateillustration, all within the true intent and broad scope of theinvention as hereinafter defined and claimed.

Fig, 1 in the drawing is a part sectional and partly diagrammatic viewillustrating a present commercial embodiment of the invention.

Fig. 2 is a broken top plan view of the same.

Basically the invention involves the provision '1 Claim. (CL 177-311) oflow tension electrodes supported in closely spaced, normally insulatedrelation in a sump or similar portion of an engine lubricating systemwhere metal chips would likely collect or be (:01- lectible, and theinclusion of such electrodes as portions of a circuit having a warninghorn, signal light or the like incorporated therein.

Preferably such electrodes are incorporated in a drain plug adapted tobe substituted in place of the conventional oil drain plug andincorporating in its make-up a magnet or magnetic means for attractingmagnetic particles to the electrodes. In the construction here shown theelectrodes and magnet feature are combined in a single plug structure bymaking the plug as a hollow body 5 externally screw threaded to fit theconventional ,magnetic electrode 8.

The center electrode is magnetized by a surrounding coil 9 and thiswinding and the electrode itself are both insulated from the plug bodyby insulation such as indicated at Ill.

The insulation mentioned may be of Bakelite or other suitable heat andoil resistant material and may be molded in and about the parts, or suchparts be otherwise suitably constructed and assembled.

For convenience of manufacture and assembly the center electrode 8 maybe made up as an iron core ll having the electrode forming head.8 at oneend and having a reduced terminal extension I 2 at the opposite end. Themagnetizing winding 9 is shown engaged about the core ll against thehead 8 and held in that relation by a washer l3 of insulating materialslipped over the terminal pin II.

The outer end of the magnet winding is shown brought out through theinsulating washer at It and there engaged or connected with the shell ofthe plug, 30 as to be grounded when the plug is screwed in the drainagefitting. The other end of the magnet winding is shown as connected at ISwith a'termin'al pin I6 extending from the insulating washer l3 parallelto the center terminal [2.

The magnet terminal pins l2 and iii are thus exposed at the end of theplug for engagement by a more or less conventional connector fitting ITon the end of the two-wire cable l8 secured in place by the sleeve I!screwed over the connector sleeve 2|] projecting from the end of theplug body.

In the simplified form of wiring diagram indi- 3 cated, both wires 2|and 22 are connected with one pole of the battery or other currentsource 23. A resistance 24 is shown interposed in the line 21 to themagnet winding to hold current down to a low value,

Also in this view the warning plug is shown connected in series with theignition switch 25 of the engine so that the.magnetizing winding will beconnected in service only when the engine is on. The normal flow in suchcase is from the battery through wire 2| to one end of the magnetizingcoil, and from the other end of that coil to ground, through the mediumof the plug body.

During normal engine operation there is no current flow through wire 22because the center electrode 8 is insulated from the body of the plug inwhich it is mounted. Metallic chips or particles, however, bridging thenarrow space between electrode 8 and the surrounding rim '5 of the plug,will establish a circuit to ground and by the inclusion of a horn, lampor other signal means 26 in this line, instant warning of such conditionwill be given.

The signal 26 may be located in the cockpit or elsewhere and there maybe several instead of just one signal. If desired, warning signals nowpresent may be utilized for this additional purpose. Thus, for example,the horn now utilized for signalling condition of the landing gear maybe used for this extra function by extending wire 22 to the same.

With current in the signal circuit kept down to a minimum it may bedesirable to put a small current sensitive relay in the signal line 22and control the signal, operating with heavier current, through thisrelay. While an electromagnet, because of its controllability andgreater electromagnetic power, may usually be preferred, it iscontemplated that a permanent magnet or magnets may be used in lieu ofthe electromagnet. In either event the magnetized or magnetic electrodehas the effect of pulling down smaller magnetic particles which due topressure circulation of the oil, might not drop from gravity alone.Hence the magnetic electrode or electrodes is or are highly desirable inthose cases where the metal may be in the form of fine particles, suchas filings, and which without the magnetic attraction might not bridgeacross the electrodes soon enough to give effective advance warning. I

The invention is readily applied and at low cost, since the parts arefewand can be relatively inexpensive. The device takes up no extra room andrequires no servicing. Connected in on the ignition circuit, it comesinto operation automatically and only when needed, that is, when theengine is operating. It is contemplated, however, that this warningsystem, if desired, may be controlled by separate switching means.

The alarm circuit will be closed by either magnetic or non-magneticchips or particles and the electrodes can be set so closely together asto activate the alarm even with the smallest sized particles which mightstart injury. Hence the alarm can be given at the earliest stage ofpossible breakdown, before the engine really begins to be injured by thechewing up of internal parts.

The invention, in fact, provides a constant check on engine operation,ready instantly to give warning of any change from safe engine operatingconditions.

The electrodes being fully exposed to the oil in circulation, willdetect the presence of metal practically as soon as it exists. Insteadof being plain circular as shown, the electrodes may be given specialshapes, the better to collect metal particles and facilitate the shortcircuiting or bridging eifect across the electrodes. Thus the edge ofthe center electrode 8 may be toothed or serrated and the inner rim ofthe plug body 5, similarly shaped, with the teeth partially meshing toshorten the magnetic and electrical gap across the same.

While of particular value for aircraft, it will be evident that theinvention is not limited thereto and is applicable to power systemsgenerally,

What is claimed is:

An engine failure advance warning device comprising an electromagneticscrew plug for mounting in the drain opening or other portion of anengine oil circulatory system, said plug consisting of an outer screwshell of metallic material, an electromagnet winding within said screwshell, a magnet core within said winding and having a head at the innerend of the same separated from the rim of the shell by a short annularmag netic gap, oil and heat resistant insulation mechanically andelectrically separating said shell and magnet core and sealing saidmagnetizing winding within the shell, an external wiring ter-- minal onthe plug connected with said magnetizing winding for association with anexternal energizing source, and a second external wiring terminal onsaid plug insulated from said first terminal and connected with saidinsulated electromagnet core.

EDMUND W. BOURNE, JR.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 570,496 Osborn Nov. 3, 18962,252,222 Van Os Aug. 12, 1941 2,317,774 Kick Apr. 27, 1943

